The general objective of this project is to elucidate the mechanisms whereby the transcription of RNA contributes to the regulation of growth. Prokaryotic and eukaryotic cells and bacterial viruses are included among the test systems. In general terms the enzymology of RNA transcription and processing is correlated with the physiological parameters of RNA synthesis and its control. For this current year important goals have included: the completion of an initial characterization of E. coli pseudouridine synthetase II, characterization in vivo of the controls over the formation of a set of tRNA synthesized by bacteriophage T4 infected cells, isolation of a possible splicing enzyme from HeLa cells. Finally a project is being carried out while the P.I. is a visitor in the laboratory of Dr. Frederick Sanger (M.R.C. Lab of Molecular Biology, Cambridge, England) to obtain the expression in E. coli of a human mitochondrial tRNA gene which has been cloned in bacteriophage M13.